1. Field of the Invention
The present invention relates to a locking device for opening or closing a door which is used in kitchen furniture and the like.
2. Prior Art
In conventional, there is a locking device for opening or closing a door, for example, as described in Japanese examined Utility Model Publication 2-2857 (corresponding to U.S. Pat. No. 4,482,175). The locking device disclosed therein comprises a lock housing 31 formed in a cabinet A for kitchen furniture and a key unit 32 formed in a door B as shown in FIG. 5. The lock housing 31 and the key unit have the relation to be fitted with each other and to be released. The lock housing 31 of the cabinet 33 has a pair of holes formed in the surface thereof in which a slider which can be moved 35 is accommodated. At the front end of the slider 35, a pair of clamps 36 and 36 which can revolve are supported. A spring member (not shown) is provided so that it is applied to a spring force to open the front ends of the clamps 36 and 36 in a V shape. At the same time, a heart-shaped groove 37 is provided on the side of the slider. A projecting member 38, one end of which slides within the slider only in one direction is provided, and the other end is formed on an appropriate position of the cabinet 33, is applied to a spring force in the direction of groove 37 by a leaf spring 39.
Consequently, when the door B in the closed state is opened, the clamps 36 and 36, which are opened in the rear surface of the door in a V shape, are brought into contact with each other in the state where a spherical member 42 of the key unit is intervened between the clamps. When the door B is further pushed toward the direction of the cabinet A, the clamps 36 and 36 are guided by rails 43 and 43 to be pushed toward inward. The clamps 36 and 36 then revolve in the direction where the open ends thereof are closed, and they clamp the spherical member 42 and move toward the direction of the cabinet A. At this time, the front end of the projecting member 38 residing within the heart-shaped groove is positioned at the recess via one side of the groove 37 to the top of the groove, and inhibits the slide of the clamps 36 and 36. The door B is locked on the cabinet A in this state.
The locking device as described above in which the leaf spring 39 is used to apply a spring force to the heart-shaped groove is disadvantageous in terms of the durability in that when the number of using the lock device is increased, the resiliency of the spring force becomes poor.
Furthermore, when the door is further pushed, the front ends of the clamps 36 and 36 are opened in a V-shape by a spring force of the spring provided on the base ends of the clamps 36 and 36 whereby the slider 35 and the clamps 36 and 36 move forward to release the locking state in the locking device disclosed therein. However, the movement is due to a spring force of the spring provided on the base ends of the clamps 36 and 36, it is difficult to smoothly move the slider 35 and the clamps 36 and 36 forward, and their actions tend to be slow.
Still further, the rollers 43 and 43 must be provided within the cabinet 33 of the locking housing 31, making the mechanism of the locking housing 31. For this reason, the device becomes a large size, and it is difficult to produce the device in a small size.
Moreover, it is difficult to correctly fix the spherical member 42 of the key unit 32 in the door side at the position opposite to the lock housing 31 and, thus, there is a tendency to have some gaps between the positions of the lock housing 31 and the key unit 32.